Caption: Cygnus constellation. 17th century artwork of a swan, representing the constellation Cygnus. This illustration is from Johann Bayer's Uranometria (Greek for 'sky measurements'), a star atlas and catalogue that contains a total of 51 stellar maps. The book, published in 1603, was the first of its kind since it portrayed the constellations as maps rather than as mythological pictures. Each engraving has a reference grid so that the stars' positions in the sky can be precisely determined.